p urr 1.] Airniial Ri'port for 1879. 
total thickness of the strata on the downthrow side. iS'o d priori objection could, 
indeed, be made on this count, for faults of very great throw are fully established ; 
it is the discrepancy of the fact with other features of the description that calls 
attention. Thus, immediately on the upthrow side of such a fault, or near it, 
patches of the highest beds of the doumthrow series may bo seen resting on the 
base-rock, which fact at once makes the fault in its primd facie asjiect impossible. 
When attention is called to this, the usual explanation is, that the fault occurred 
before that upper group was deposited. This assertion is not so easily disposed 
of, but I consider that in the cases before us it is in a great measure disposed of: 
it may, I think, be hold as impossible that disturbance of such magnitude as is 
implied by a fault of several thousand feet throw could take place between two 
groups of a stratified series, and not produce far greater effects of discordance 
than have as yet been observed between any groups of the Gondwana series. I 
do not forget that I have myself illustrated the compatibility of complete apparent 
conformity with synchronous great disturbance in the inimodiato vicinity (IVlanual, 
pp. 550-51); but that case rather enforces than invalidates the remarks I have 
just made: if the apparent discrepancy to which 1 have called attention were 
susceptible of an analogous interpretation, the notice of the feature as a simple 
fault would be none the less mi.sleading. I would again invite my colleagues to 
a more critical attention to their ‘faults’: an erroneous fault within the stratified 
series may only lead to mistakes in calculating the positio7r of any particular 
bed; but a mistake as to the nature of a main boundary leads ns altogether 
astray in judging of the original conditions of the formation, tac disco\ei’y of 
which is a principal object of our study. Thus, for this Gondwana formation, 
it is generally supposed to be in the main of subaerial origin, by rain and rivers, 
and presumably accumulated ui^on an area of subaerial erosion; j-et the ever 
I’eady introduction of faults, pure and simjDle, at the limits of the basins, leavms 
this supposition out of sight. 
In Kattywar, which belongs to the peninsular area, on the southern confines 
Katiswab: of the Arvali metamorphic region, IMr. Feddcn completed 
Mr. Feddcn. the survey of some 1,900 square miles (sheets 24, 25, and 
36) in continuation to the south of his juevious season s wmi’k, besides making 
some preliminary traverses of adjoining ground. "W ith the exception of a small 
inlier of Upper Gondwana (juras.sic) I’ocks of the Umia horizon near Mewasa, 
and very local outcrops of a sandstone locally underlying the ti-ap, but containing 
trappean debris, the wdiole area is occupied by the great eruptive formation. It 
is mostly stratified, having a slight inclination to the south, but huge dykes tra¬ 
verse it in various directions, forming prominent ridges across the low undulat¬ 
ing country. Terraces of the marine miliolitic limestone occur locally halfuaij 
up the sides of these ridges. The marble of local rejmto as Gondal marble 
is only an iri'egular spariy vein in the trap, not jnoro than 21^ feet wide; 
it occurs at Khirsara and Sajriali, 15 miles north-west of Dhoraji. A cur¬ 
sory visit was made to the famous Junagai’h hills, the volcano-like construction 
of which was early noticetl, but wdiich wore said to be in part formed of gneissic 
or granitic rocks. The isolated central hill forming the sacred peak of Girnar is 
a mass of thoroughly crystalline rock, a granular coinpound of a clear plagioclaae 
